In the related art, there is known a technology of detecting a facial region of a person from captured images of a person captured by a camera for the purpose of face authentication, face collation, and the like. Such a facial detection technology detects eyes, a nose, a mouth, and the like, which are feature portions of a face, from captured images as facial feature points and detects a facial region based on the detected facial feature points (for example, PTL 1).